A. Technical Field
The present invention relates to a transponder for receiving a wireless electromagnetic interrogation signal and for transmitting a wireless electromagnetic response signal with a first coil acting as an antenna for generating a first wired electrical receive signal from the interrogation signal, and with at least one further coil acting as an antenna for generating a further wired electrical receive signal from the interrogation signal, wherein an axis of the first coil and an axis of the further coil are aligned differently in the space.
B. Background of the Invention
A transponder having three coils which are each arranged orthogonally to each other is known from EP0783190A1. Here, the signals of the three coils are in each case rectified by means of a diode and are used for charging a capacitor arrangement. The direct current voltage applied to the capacitor arrangement is then used as supply voltage for the transponder. By using the three coils arranged in each case orthogonally to each other, the supply voltage can be provided substantially independent of the transponder's position and spatial orientation with regard to the interrogator generating the interrogation signal.
However, in this manner, it is not possible to generate from the interrogation signal a time base signal which corresponds with the frequency of the interrogation signal and which may be required for synchronizing the transponder with the interrogation device.